Package com.illumon.iris.db.v2.utils

Class CumulativeUtil

java.lang.Object

com.illumon.iris.db.v2.utils.CumulativeUtil

public class CumulativeUtil
extends Object

Utilities for cumulative and rolling aggregations.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CumulativeUtil.CumulativeFilterHelper	Provides a helper class with a map to cache previous row values when performing filtering of data whose values change from row to row.
static class	CumulativeUtil.CumulativeHelper	Provides a helper class with a map to cache previous row values when performing rolling or cumulative aggregations.

Constructor Summary

Constructors

Constructor	Description
CumulativeUtil()

Method Summary

Modifier and Type	Method	Description
static Table	accumulate(Table t, String key, double startValue, String newCol, String formula)	General purpose core method for executing running and cumulative aggregations.
static Table	cumMin(Table t, String newCol, String formula)	Executes a cumulative aggregation of the minimum value so far for a formula.
static Table	cumSum(Table t, String newCol, String formula)	Executes a cumulative sum aggregation far for a formula.
static Table	cumSum(Table t, String key, String newCol, String formula)	Executes a cumulative sum aggregation far for a formula.
static Table	filterChanged(Table t, String key, String col)	Returns only rows for which the selected column value is different from the value in the previous row.
static void	main(String... args)	main method to show examples of use of this class' methods.
static Table	rollingSum(Table t, int windowSize, String newCol, String formula)	Executes a rolling sum aggregation far for a formula.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CumulativeUtil

public CumulativeUtil()

Method Details

accumulate

public static Table accumulate(Table t,
 String key,
 double startValue,
 String newCol,
 String formula)

General purpose core method for executing running and cumulative aggregations. Used by helper methods which provide template formulae for specific types of aggregations.

Parameters:

t - The Table to use as input to the aggregation.

key - Nullable string key to use to access the cached previous row value within the CumulativeUtil.CumulativeHelper map. Note that a non-null literal key must be enclosed in backticks since it will be used in a formula. Typically a column expression, rather than a literal, is used to allow operations based on the grouping of the expression.

startValue - Initial value from which to start aggregating. Normally 0.

newCol - The name of the aggregation column to add to the table.

formula - A formula indicating how to calculate the aggregation. This is normally provides by a helper method. An example would be something like: "_prev+A" to cumulatively sum A.

Returns:

A Table with the new aggregation column added. Note that this column will be a double column, regardless of the numeric type(s) of the formula input(s).

cumMin

public static Table cumMin(Table t,
 String newCol,
 String formula)

Executes a cumulative aggregation of the minimum value so far for a formula.

Parameters:

t - The Table to use as input to the aggregation.

newCol - The name of the aggregation column to add to the table.

formula - A formula for the source value on which to calculate a running minimum. This can be as simple as the column name or a more complex expression.

Returns:

A Table with the new aggregation column added. Note that this column will be a double column, regardless of the numeric type(s) of the formula input(s).

cumSum

public static Table cumSum(Table t,
 String key,
 String newCol,
 String formula)

Executes a cumulative sum aggregation far for a formula.

Parameters:

t - The Table to use as input to the aggregation.

key - Nullable string key to use to access the cached previous row value within the CumulativeUtil.CumulativeHelper map. Note that a non-null literal key must be enclosed in backticks since it will be used in a formula. Typically a column expression, rather than a literal, is used to allow operations based on the grouping of the expression.

newCol - The name of the aggregation column to add to the table.

formula - A formula for the source value on which to calculate a running sum. This can be as simple as the column name or a more complex expression.

Returns:

A Table with the new aggregation column added. Note that this column will be a double column, regardless of the numeric type(s) of the formula input(s).

cumSum

public static Table cumSum(Table t,
 String newCol,
 String formula)

Executes a cumulative sum aggregation far for a formula.

Parameters:

t - The Table to use as input to the aggregation.

newCol - The name of the aggregation column to add to the table.

formula - A formula for the source value on which to calculate a running sum. This can be as simple as the column name or a more complex expression.

Returns:

A Table with the new aggregation column added. Note that this column will be a double column, regardless of the numeric type(s) of the formula input(s).

rollingSum

public static Table rollingSum(Table t,
 int windowSize,
 String newCol,
 String formula)

Executes a rolling sum aggregation far for a formula.

Parameters:

t - The Table to use as input to the aggregation.

windowSize - The number of rows to include in the rolling sum window.

newCol - The name of the aggregation column to add to the table.

formula - A formula for the source value on which to calculate a running sum. This can be as simple as the column name or a more complex expression.

Returns:

A Table with the new aggregation column added. Note that this column will be a double column, regardless of the numeric type(s) of the formula input(s).

filterChanged

public static Table filterChanged(Table t,
 String key,
 String col)

Returns only rows for which the selected column value is different from the value in the previous row.

Parameters:

t - The Table to use as input to the method.

key - Nullable string key to use to access the cached previous row value within the CumulativeUtil.CumulativeHelper map. Note that a non-null literal key must be enclosed in backticks since it will be used in a formula. Typically a column expression, rather than a literal, is used to allow operations based on the grouping of the expression.

col - The column to check for changing values.

Returns:

A Table of only rows where the selected value has changed from the value in the previous row.

main

public static void main(String... args)
                 throws IOException

main method to show examples of use of this class' methods.

Parameters:

args - Not used

Throws:

IOException